I’ve often heard the differences between the imperial and metric measurement systems discussed, and occasionally someone will state whichever one they believe is superior. This has caused me to wonder how the United States came about the imperial system, but when I researched the subject, I came to a startling realization: I was lied to.
Well technically, in all fairness, the people that “lied” when they said the United States uses the imperial system were most likely misinformed as I was. It turns out that some countries do still use the imperial system, such as Liberia and Myanmar (which are apparently transitioning to the metric system), and interestingly, the United Kingdom and Canada use a mixture of the imperial and metric systems, however, contrary to popular belief, the United States does not use the imperial system.
Officially, the United States uses the US Customary System, which does use many of the same units that the imperial system uses, however, the US Customary System was standardized long before the British Imperial System was.
Fun fact: though it is not an official nickname, I’ve heard the US Customary System called Freedom Units, which I think rolls off the tongue much better.
How the United States Adopted the Customary System
The English settlers that founded what would become the thirteen colonies brought their units of measurement to North America. After gaining their independence, the thirteen colonies — which had now become the United States — continued to use the British units that they were accustomed to.
In 1832, the United States adopted a set of standards for this measurement system for customs houses, which is likely why the system is called the customary system.
There’s a Unit for That!
One of the most common arguments I’ve heard people make for the metric system is that it has many types of units for all kinds of applications, and they are all base-10, meaning it is easy to convert between them.
Yes, it is pretty slick to just move a decimal point to convert between units, but if you grow up with the customary system, it isn’t difficult to convert between these units. I also find their boasts about their customizable units rather interesting, especially because they don’t use them to their fullest extent.
In the United States, we may consider a glass to be 8 ounces, which is a decent number to work with, however, the rest of the world might mention a 250 milliliter glass — 250! Why use your small units for such an application? Why not 25 centiliters, or 2.5 deciliters? Why say 1 billion liters when you could say 1 gigaliter? Why 1,000 kilometers and not 1 megameter?
And to address the statement that a gram is much more accurate than an ounce: while this may be true, have you not heard of the grain that is much smaller than a gram?
The customary system does in fact have a unit to match most of the common metric units. Here is a quick list of some metric units and their approximate equivalent in customary units.
| Metric | US Customary | Ratio |
|---|---|---|
| Milliliter | Teaspoon | 0.20 |
| Liter | Quart | 1.06 |
| Millimeter | Thou | 39.4 |
| Centimeter | Inch | 0.39 |
| Meter | Yard | 1.09 |
| Kilometer | Mile | 0.62 |
| Calorie | BTU | 3.97 |
| Gram | Grain | 15.4 |
| Kilogram | Pound | 2.20 |
What do you think about the US Customary System?
Onward American 